Currently there are at least two different techniques that a user of a mobile telephone can utilize in order to input text messages. The first technique is to utilize the numeric input buttons of the mobile phone to input characters, which can be slow and tedious considering that some characters and techniques involve several key depressions per character. A second technique is for the mobile phone to be enabled with a capacitive sensor and character recognition abilities such that its user is able to gesture or “write” with his or her finger over its buttons (without depressing the buttons) in order to input alphanumeric characters. This provides a quicker way for entering text into a mobile phone. Additionally, gestures can also be used to navigate through the mobile phone operating system and/or menus. However, there are disadvantages to the conventional techniques for fabricating the capacitive sensors associated with the finger gesture input.
For example, a conventional technique is described in PCT publication WO 02/100074 (the U.S. relative is published as US 2003/0025679) in which the capacitive sensor of a mobile phone includes holes to allow keypad posts to pass through in order to activate switches associated with depressed keys. One of the disadvantages of this conventional technique is that it involves a lot of compensation in the sensing circuitry of the capacitive sensor to accommodate the irregular sensor design associated with routing around the holes. As such, this type of capacitive sensor can require increased development effort, time, and expense to adapt to different electronic devices, since the compensation usually has to be customized for each hole layout, and reconfigured when the key post holes are rearranged.
The present invention may address one or more of the above issues.